The present invention relates to an apparatus and method to determine and store certain operational data regarding the historical performance of various gripping and pivot mechanisms disposed on a robotic accessor disposed within an automated data storage system. The present invention further relates to an apparatus and a method to access and graphically depict that stored historical performance data to assist the diagnosis of the cause of an accessor failure.
Automated media storage libraries are known for providing cost effective access to large quantities of stored media. Generally, media storage libraries include a large number of storage slots on which are stored portable data storage media. The typical portable data storage media is a tape cartridge, an optical cartridge, a disk cartridge, and the like. One (or more) accessor typically accesses the data storage media from the storage slots and delivers the accessed media to a data storage drive for reading and/or writing data on the accessed media. Suitable electronics both operate the accessor and operate the data storage drives to transmit and/or receive data from an attached on-line host computer system.
In a conventional automated media storage library, the storage slots are arranged in a planar orthogonal arrangement forming a xe2x80x9cwallxe2x80x9d of storage slots for holding data storage media. The plane may be a flat plane, or may be a cylindrical plane. To double the storage capacity, two xe2x80x9cwallsxe2x80x9d of storage slots may be provided on either side of the accessor.
A number of different companies manufacture automated media storage libraries today, each model displaying various different features. One example is the IBM 3494 Media Storage Library. Some of the automated media storage libraries have dual or multiple accessors to provide a level of redundancy.
Occasionally, an accessor may become unavailable, for example, if a component of the accessor must be replaced or repaired. In the event of an accessor failure, the cause of the failure must first be ascertained before a repair can be made. What is needed is an apparatus and a method to store operational information about each accessor, and an apparatus and a method to make that stored information readily available in the event of an accessor failure.
Applicants"" invention includes an automated data storage system comprising one or more accessors for retrieving a plurality of data storage media stored in a plurality of storage slots, and for delivering that retrieved data storage media to one or a plurality of data storage drives for reading and/or writing data thereon. Each such accessor comprises an accessor control card, a revolving memory buffer resident on the accessor control card, and a velocity control program resident on the accessor control card.
In one embodiment of Applicants"" invention, each such accessor further includes a first gripper, a first gripper motor disposed on the first gripper, and a first gripper motor tach disposed on the first gripper motor, such that the first gripper tach provides, at a first time, first gripper motor tach information to the velocity control program. Each such accessor further includes a pivot motor and a pivot motor tach disposed on the pivot motor, such that the pivot motor tach provides, at a first time, pivot motor tach information to the velocity control program. In this embodiment, the velocity control program stores the first gripper motor tach information and the pivot motor tach information in the revolving memory buffer.
In other embodiments, Applicants"" accessor further includes a second gripper, a second gripper motor disposed on the second gripper, and a second gripper motor tach disposed on the second gripper motor, such that the second gripper motor tach provides, at a first time, second gripper motor tach information to the velocity control program. In these alternative embodiments, the velocity control program stores the first gripper motor tach information, the second gripper motor tach information, and the pivot motor tach information in the revolving memory buffer.
Applicants"" invention also includes a method to diagnose the failure of an accessor using the information stored in the revolving memory buffer of that defective accessor. When using accessors having two gripper mechanisms, Applicants"" method includes generating first gripper motor tach information using the first gripper motor tach; storing a first tach position, a first demand velocity, a first PWM voltage, and calculating and storing a first actual velocity; generating second gripper motor tach information using the second gripper motor tach; storing in said revolving memory buffer, a second tach position, a second demand velocity, a second PWM voltage, and calculating and storing a second actual velocity; generating pivot motor tach information using the pivot motor gripper tach; storing a third tach position, a third demand velocity, a third PWM voltage, and calculating and storing a third actual velocity; generating at a second time updated first gripper motor tach information, updated second gripper motor tach information, and updated pivot motor tach information; and determining if an accessor failure has occurred.
In the event an accessor failure occurs, the operational data stored in the accessor""s revolving memory buffer can be downloaded to an external computer. That downloaded data can then be graphically displayed in order to diagnose the cause of the accessor failure.